The Picts beyond the Black River are uniting under the sorceries of the wizard Zogar Sag, and preparing to drive the colonising Aquilonians back over Thunder River and out of Pictish territory forever. On a mission to kill Zogar Sag, Conan's small band of men are ambushed, but he is able to rescue one comrade from the swamp devils controlled by Zogar. It is now up to these two to get the colonists to the safety of Velitrium before the Picts destroy everything in a red ruin.